Grand Junction, CO(KKCO)-Another surge of subtropical moisture will get drawn north into eastern Utah later today then spread into western Colorado late this afternoon and evening. A shortwave trough will carry this moisture into the area as it moves north northeast from southern Arizona and merges with minor shortwave lifting out of a pacific trough. The forecast model appears to be doing a very good job with the current situation and shows the vorticity center over southern Arizona in about the same position as current satellite images. After 3pm today, the forecast model shows this trough lifting northeast over west-central and northwest Colorado. The model also shows a strong emphasis for rain over northeast Utah and northwest Colorado this afternoon and evening along with increased cloud cover across the area today and tonight.
Thursday and Thursday night the relatively high chance or rain should continue as a shortwave trough moves through the area from the west. By Thursday evening this trough should push drier air into the area from northwest to southeast.
A ridge begins to build again over the region Friday and should help reduce showers and thunderstorms with lingering storms over the higher terrain mainly south. The ridge axis increases in amplitude and shifts to the east through the first part of the weekend. This shift allows an increase in moisture form the southwest for the second half of the weekend and into early next week. In addition, a pacific trough moves inland and over the northern Rockies early next week. The trough should bring an increase in upper level dynamics. Slightly better confidence with the models, as run to run and model to model show more consistency. Therefore, an increased chance of rain over for the first part of next week accordingly.
Moisture will linger over eastern Utah and western Colorado into the middle of next week. Temperatures will remain near or just above normal through the extended forecast.
Source: National Weather Service: Grand Junction, CO